The invention relates to a roller assembly for a motor vehicle having a rotatably supported winding shaft, a flexible fabric sheet which when in a stowed condition is wound onto the winding shaft and which can be unwound in a longitudinal direction in order to reach a functioning position and which has sliding elements on its side edges, two guide rails extending in the longitudinal direction to guide the sliding elements that are attached to the side edges of the fabric sheet, and a frame. The guide rails are here constructed such that they can be fastened with variable transverse distance on the frame so that a desired distance can be permanently fixed through this fastening.
Roller assemblies are used for a variety of purposes in motor vehicles. In particular they may be implemented as covers for freight compartments, as partition nets or as roller shades. The said roller shades can here be used both at essentially vertically aligned window surfaces and on essentially horizontal window surfaces, roof windows in particular.
Not exclusively, yet nevertheless particularly in connection with the said roof windows, it is of great importance that the fabric sheet does not sag to an unacceptable degree when in its functioning position. Since the material properties of the fabric sheet are not always entirely uniform, this must nevertheless be feared if the guide rails that guide the fabric sheet at the sides are mounted at a fixed distance from one another and are therefore separated by the same distance on all roller assemblies of the same type.
Generic roller assemblies counter this by having two guide rails that can be attached to the frame with a variable spacing. In this way it is possible, when the material properties or the cut sizes of the fabric sheet differ by small amounts, for an adjusted spacing of the guide rails nevertheless to ensure an at least substantially consistent sag of the fabric sheet, of a small and acceptable degree, for roller assemblies of the same design. This adjustment is carried out in the course of assembly, usually before the roller assembly is delivered to the vehicle manufacturer.
Electric motors are usually used with the roller assemblies that are fitted into motor vehicles, in order to move the fabric sheet between its stowed position and its functioning position. In order to transfer the force from the usually single electric motor that applies force to both sides of the fabric sheet, a drive chain designed to transmit both tensile and compressive forces, and held in a guide tube between the drive unit and the particular guide rail, may be used. It has nevertheless been found that ensuring the proper function of a generic roller assembly with such drive chains and guide tubes is problematic if the guide rails can have a variable spacing in the transverse direction. It has also been found that feed-in pieces attached to the guide rails for the sliding elements of the fabric sheet, or indeed for the drive chain, and which, due to the variable spacing between the guide rails, are only attached to these guide rails and not directly to the frame, move with respect to the associated guide rail in spite of being attached to them as a result of the force exerted by the drive chain, and can then cause the roller assembly to malfunction.